Răspuns :
[tex] \frac{30x}{100} + \frac{20}{100} \times \frac{30x}{100} + 320 = x \\ \\ 3000x + 600x + 3200000 = 10000x \\ \\ 3200000 = 10000x - 3600x \\ \\ 3200000 = 6400x \\ \\ x = 500 \: participanti [/tex]
30% x 500 = 30x500:100 = 150 tricouri albe
20% x 500 = 20x500:100 = 100 tricouri rosii
50% x 500 = 50x500:100 = 250 tricouri albastre
320-250 = 70 tricouri
30% x 70 = 21 tricouri alb-albastre (din cele 150albe)
20% x 70 = 14 tricouri ros-albasre (din cele 100 rosii)